| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a gain control amplifier circuit which does not cause the deterioration of saturated output power even at the time of a large input signal, reduced in the distortion of voltage and reduced in the fluctuation of power consumption. SOLUTION: Concerning first and fourth transistors 13 and 16 the bases of which are connected to a first bias power source 20 outputting so-called AGC voltage, when an input signal is reduced, an emitter current is reduced and the emitter input impedance of respective transistors 13 and 16 is increased and on the other hand, the emitter currents of second and third transistors are increased and the amplification degree of both transistors are increased to amplify the input signal. On the other hand, when the input signal is increased, the emitter currents of the first and fourth transistors 13 and 16 are increased to deteriorate emitter input impedance to attenuate the input signal but the emitter currents of the second and third transistors are reduced to deteriorate the amplification degree of both transistors 14 and 15 to prevent an output signal from coming into a level more than a necessary level.</p> |
